The present invention relates to construction equipment, such as cranes or bulldozers, that utilize continuous tracks or crawler assemblies for lateral movement of the vehicle. In particular, the present invention relates to a crawler crane or crawler vehicle having identical left and right crawler assemblies.
In a conventional crawler crane, each crawler is typically powered by a hydraulic motor mounted directly on the crawler. Each hydraulic motor is connected to a hydraulic pump located on either the lower or upper works of the crane by as many as four hydraulic hoses. The hydraulic motors are typically located on the interior surface of the crawler frames near the forward end of the crane. The crawler assemblies are therefore symmetric about the centerline on the crane lower works. Consequently, each crawler assembly has a unique design and requires individual components and mounting configurations. In other words, a conventional crawler crane has separate left-hand and right-hand crawler assemblies, each assembly having a unique design and configuration.
A more recent crawler crane design utilizes hydraulic drive motors that are mounted on the crane lower works. Each hydraulic drive motor is connected to a crawler by a mechanical drive shaft that may be disassembled to permit removal of the crawler from the lower works of the crane without disconnecting the hydraulic motors from the hydraulic pump. This more recent crawler crane design is also symmetric about the centerline of the crane and therefore also utilizes individually designed and manufactured left-hand and right-hand crawler assemblies.
Crawler assemblies are costly to design and manufacture. These costs are increased by the use of separate left-hand and right-hand crawler assemblies. In particular, each crawler assembly must be designed and manufactured separately. For example, each crawler assembly requires the fabrication of a unique crawler frame and track frame weldment, and a unique mounting arrangement for the crawler drive assemblies. Other components used in the crawler assemblies must likewise be individually designed and manufactured for each individual crawler assembly. Utilization of identical crawler assemblies will reduce the number of individually designed and fabricated components, thereby reducing the manufacturing cost of the crawler assemblies.
Non-identical crawler assemblies also increase the cost of servicing or repair of the crane. For example, the crane operator or manufacturer often maintains replacement or spare crawler assemblies in the event that one of the crawler assemblies fails or is damaged. With a conventional crane design, it is necessary to maintain separate left-hand and right-hand drive assemblies. Utilization of identical crawler assemblies eliminates the need to purchase and maintain two complete crawler assemblies or different sets of components.